Billionaire Wall Street financier Peter Peterson, who co-founded private equity firm Blackstone and served as US President Richard Nixon’s commerce secretary, died on Tuesday of natural causes, his family said. He was 91. “As a first-generation American born in Kearney, Nebraska, Pete exceeded all of his expectations in becoming a successful businessman, statesman and philanthropist,” the Peterson family said in a statement. The son of Greek immigrants who operated a diner in Kearney, Mr Peterson founded Blackstone in 1985 with Stephen Schwarzman, with an initial investment of $200,000 (£142,836).